Lighting patterns and the flow of light

The pattern of light and shade on a solid object due to directional lighting is the combined effect of three lighting patterns, identified as the illumination, shadow and highlight patterns. The illumination pattern is examined in detail as the nature of its formation relates to the subjective impression of a 'flow of light' within a room. Indices of the flow of light are proposed, and the extent to which they relate to the formation of lighting patterns on solid objects is examined. Design recommendations based on observations of the human features are proposed.